Such a container is known from the European Patent EP-A-002082.
In this patent a bottle is described which is made of oriented thermoplastic material, such as vinyl chloride-based resins, polymers and co-polymers of acrylic acid or polyesters such as polytherephtalate of ethyleneglycol. In order for the known bottle to have a better resistance to deformation due to build-up of internal pressures and to lateral shocks, such as occur when the bottle is dropped during transportation, the central dome-shaped part has a certain minimum diameter, preferably less than 40% of the total diameter of the bottle.
After blow-moulding of bottles of thermoplastic material, it is for fast production of the bottles required that they release easily from the mould. To reduce the production cycle time, the bottles are released from the mould at the limiting condition of the bottles, and especially the base, being solid but still hot. Bottles having a central dome-shaped part of too small a diameter will, upon opening of the mould, release with difficulty and require removal from the mould by mechanical loosening means or by hand.
Bottles of thermoplastic material that are optimized according to strength, i.e. having relatively thick walls, rather than by using a minimum amount of material, have as a disadvantage that during blow moulding of the bottles, the cooling of the bottles takes longer, such that production rates will be lowered.
It is also known to reinforce the base of bottles of thermoplastic material by, instead of forming a central dome-shaped part, providing the base with a reinforcement rim, or by providing the base with a number of reinforcing depressions. It was found that for bottles containing products such as a bleach containing for example 2% of chlorine were still subject to outward bulging of the base despite reinforcement thereof at elevated temperatures (50.degree. C. and higher) due to large internal pressure build-up. This makes the bottles unstable in the upright position, causing them to fall off shelves or toppling over in kitchen cabinets.